It may have been the weekend, but there has been no rest for the News of the World phone-hacking scandal. In just three days it has caused the top UK police chief to resign, seen — until very recently — a top News Limited executive arrested and forced Rupert Murdoch to publicly apologise.

Metropolitan Police Commissioner Sir Paul Stephenson announced his resignation after it became public that Neil Wallis, a deputy editor at NotW who was arrested last week, had been hired in recent years as a communications consultant for the Met.

In a statement, Stephenson stressed that he had no idea that Wallis was involved:

“I have taken this decision as a consequence of the ongoing speculation and accusations relating to the Met’s links with News International at a senior level and in particular in relation to Mr Neil Wallis who as you know was arrested in connection with Operation Weeting last week …

“I have heard suggestions that we must have suspected the alleged involvement of Mr Wallis in phone hacking. Let me say unequivocally that I did not and had no reason to have done so. I do not occupy a position in the world of journalism; I had no knowledge of the extent of this disgraceful practice and the repugnant nature of the selection of victims that is now emerging; nor of its apparent reach into senior levels.”

In a move that may leave PM David Cameron facing some difficult questions, Stephenson also said he had kept appointment of Wallis quiet in order to protect Cameron from his involvement in the scandal since Cameron hired former News of the World editor Andy Coulson as his chief spinner.

“I am aware of the many political exchanges in relation to Mr Coulson’s previous employment — I believe it would have been extraordinarily clumsy of me to have exposed the prime minister, or by association the home secretary, to any accusation, however unfair, as a consequence of them being in possession of operational information in this regard.”

Cameron’s office bowed to pressure yesterday and released a memo revealing that Cameron has met with News Limited executives a whopping 26 times since becoming Prime Minister a year ago. That includes two trips to Chequers, the country estate of the UK PM, for Rebekah Brooks, the former NotW editor with the fiery mane, a privilege most of his most senior cabinet colleagues have not received, says The Independent.

Meanwhile, Brooks has been identified as a criminal suspect and arrested by police over her involvement in alleged police bribes and phone hacking. Scotland Yard arrested her at noon yesterday and kept her in for questioning all day. She’s the 10th person to be arrested by police over the NotW scandal. Police have two separate operations to examine the NotW scandal, Operation Weeting, which examines hacking into voicemails of mobile phones and Operation Elveden, which investigates the alleged £130,000 paid to police officers for information by NotW

Brooks announced her resignation from her News executive position on Friday, saying in a statement that her remaining in her position was “detracting attention from all our honest endeavours to fix the problems of the past”.

Brooks had been asked to appear for an appointment at the police station on Sunday, but according to a spokesperson, the arrest came as a surprise. It also comes as a surprise to others who were wanting to question Brooks at a parliamentary inquiry into the phone-hacking scandal on Tuesday. Mark Lewis, lawyer for the family of Milly Dowler, the murdered 13-year-old whose voicemail was hacked, questioned the police’s decision to arrest Brooks now:

“Undoubtedly she will have the option of saying on Tuesday, ‘I’m sorry I can’t answer that because I’m under police investigation’… The timing stinks … It gives the impression that those questions can’t be asked [now] … It looks deliberate.”

News is in damage control, as it tries to clean up its seeping mess. National papers in the UK ran a full-page mea culpa signed by chief Rupert Murdoch over the weekend:

But the police handling of this crisis may be even more destructive. As Don Van Natta jnr writes in The New York Times, serious mistakes were made by Scotland Yard due to its cosy relationship with News Corp.

“For nearly four years they lay piled in a Scotland Yard evidence room, six overstuffed plastic bags gathering dust and little else.

Inside was a treasure-trove of evidence: 11,000 pages of handwritten notes listing nearly 4000 celebrities, politicians, sports stars, police officials and crime victims whose phones may have been hacked by The News of the World, a now defunct British tabloid newspaper.

Yet from August 2006, when the items were seized, until the autumn of 2010, no one at the Metropolitan Police Service, commonly referred to as Scotland Yard, bothered to sort through all the material and catalogue every page, said former and current senior police officials …

At best, former Scotland Yard senior officers acknowledged in interviews, the police have been lazy, incompetent and too cozy with the people they should have regarded as suspects. At worst, they said, some officers might be guilty of crimes themselves.”